Horn, C. N. 1987. Pontederiaceae. Flora of Ecuador 29: 3-19.

Novelo R., A. and A. Lot H. 1994. Hydrocharitaceae. Pp. 10-12 in Davidse, G., Sousa, M. and Chater, A. (eds.). Flora Mesoamericana 6: 1-543. Universidad Nacional Autónoma de México: México, D. F.

7 genera and ca. 36 spp.; chiefly tropical, especially New World, extending in northeastern North America to S. Canada; some widely cultivated in water gardens of warm regions; 3 genera, 10 spp. in CR.

Annual or perennial aquatic herbs; submerged, floating, emergent or creeping on mud. Lvs. simple with entire margins, sheathing at base, alternate and distichous or forming a basal rosette, linear and/or petiolate with blades lanceolate to orbicular, cuneate to cordate or sagittate at base. Fls. zygomorphic to nearly actinomorphic, bisexual, often heterotristylic, solitary or infl. spicate, racemose, paniculate or umbelliform, subtended by 2 spathes, one of which may be leaf-like. Perianth petaloid, united into a tube, white, yellow, blue, often with distinctive markings toward throat of tube [yellow on blue, purple on white]. Stamens 6, 3, or 1 fertile with 2 staminodes, inserted on the perianth tube. Ovary superior, 3-locular; style 1. Fr. typically a capsule, sometimes a 1-seeded nut enclosed in a hardened perianth base (anthocarp) (Pontederia); seeds numerous or solitary.

As an aquatic group, the Pontederiaceae tend to be under collected and the distribution of the taxa are believed to be wider than specimens indicate. Often specimens are collected representing only the upper portion of the plant, thus excluding the morphologically different underwater leaves.

1. Petiolate leaves with blades cuneate to truncate at base.

2. Flowers numerous, borne in a spike; stamens 6; leaf blades thickened...Eichhornia

 

2. Flowers solitary; stamens 3; leaf blades thin, narrowly to sometimes broadly lanceolate...Heteranthera limosa

1. Petiolate leaves with blades cordate to sagittate at base.

3. Plants with numerous alternate sessile, linear submersed leaves and with floating petiolate leaves with cordate to nearly round blades (often sterile, with only the submersed leaves)...Eichhornia diversifolia

 

3. Plants typically lacking sessile leaves, or, if present, then basal, in a rosette (juvenile stage a basal rosette of linear leaves).

4. Inflorescence paniculate...Eichhornia paniculata

 

4. Inflorescence spicate or flowers solitary.

5. Flowering stem with a constriction just below the first node; inflorescence a densely crowded spike; stamens 6; fruit a single seeded nut with ridges (utricle/anthocarp)...Pontederia

 

5. Flowering stem without a constriction; flowers solitary or in a sparsely flowered spike; stamens 3; fruit a many-seeded capsule...Heteranthera

Agostini, G. 1974. El genero Eichhornia (Pontederiaceae) in Venezuela. Acta Bot. Venezuelica 9: 303-310.

Ca. 7 spp., chiefly tropical America, 1 in Africa. Eichhornia crassipes widely introduced in tropical and subtropical regions of the world.; 5 spp. reported for CR.

Perennial or annual. Stems floating, strongly stoloniferous, or stranded and creeping. Submersed leaves sessile, linear, ribbon-like, forming a basal rosette, or alternate along the submerged portion of stem. Juveniles consisting of a rosette of submersed linear leaves. Emergent or floating leaves petiolate, the blades cuneate to truncate or cordate at base. Sometimes both submersed linear leaves and petiolate floating or emergent leaves present. Inflorescence a spike, panicle or few-flowered umbel, subtended by 2 spathes, the lower leaf-like, the upper forming a sheath. Flowers blue to pink or white. Perianth tubular, 6 lobed, the upper one larger, often with a distinct yellow or purple marking. Stamens 6, borne at 2 levels on perianth tube, filaments bearing glandular hairs. Fruit a capsule, seeds numerous.

Eichhornia paniculata (Sprengel) Solms-Laub., a plant with basal leaves, cordate leaf bases and a paniculate inflorescence, has been collected from temporary ponds in Dept. Rivas, Nicaragua, and might be expected in such habitats in northwestern Guanacaste.

1. Plants floating (sometimes stranded on mud); vegetative stem very short with leaves in a rosette, somewhat erect to widely spreading, petioles broadly swollen, almost bulbous, filled with aerenchymatous tissue (or, when plants growing densely crowded, leaves erect, petioles less swollen)...E. crassipes

1. Plants rooted; vegetative stem short, leaves basal, ascending, emergent in shallow or rooted in mud near edge of water, or, stems very elongate, submerged and typically reaching surface and then floating; petioles not swollen.

2. Vegetative stem short, petiolate leaves basal; inflorescence umbelliform...E. paradoxa

 

2. Vegetative stems long, petiolate leaves alternate, floating, or petioles strongly bent, holding blades more or less emergent from floating stems; inflorescence spicate.

3. Petiolate leaf blades cordate at base, less than 3 cm long, blades typically floating; submersed alternate, sessile, cauline leaves present (frequently, when sterile, only submersed leaves present); inflorescence 1-3 flowered...E. diversifolia

 

3. Petiolate leaf blades cuneate to truncate at base, 3-16 cm long, blades typically held somewhat emergent; submersed leaves alternate, sessile, cauline, present (especially on younger stems) or absent by deterioration; inflorescence 7-many flowered.

4. Leaf blades 3-9 cm long; flowers blue or white with a violet spot on upper central perianth lobe, perianth lobes 8-10 mm long, margins entire; inflorescence glabrous or nearly so...E. heterosperma

 

4. Leaf blades 7-17 cm long; flowers blue or white with yellow or deep purple spot on upper central perianth lobe, perianth lobes 13-25 mm long, margins erose or somewhat fimbriate; inflorescence densely pubescent...E. azurea

Eichhornia azurea (Sw.) Kunth, Eichhornia 4. 1842. [Pontederia azurea Sw., Nov. Gen. Sp. Prodr. 57. 1788].

Plants rooted in mud, with elongate stems ascending to water surface. Submerged leaves cauline, alternate, sessile, linear and ribbon-like, (specimens typically collected without obtaining submersed leaves). Petiolate leaves with petioles strongly bent, holding blades more or less emergent from floating stems, leaf blades 7-17 cm long, cuneate to truncate at base. Inflorescence densely glandular pubescent. Flowers white or violet (drying blue), with a large deep purple spot toward the throat of the perianth tube on upper central perianth lobe and a small yellow dot just above the large purple spot. Perianth lobes 13-25 mm long, margins erose. Fruit ca. 1 cm long.

Lagunas. Known only from Llanuras Tortugero and Guatusos [Crow 7720, CR; Robles 1383, MO], Nov. S. Mex. to Bolivia and Argentina; Antilles.

Eichhornia crassipes (C. Martius) Solms-Laub. in A. DC and C. DC., Monogr. Phan. 4: 527. 1882. [Pontederia crassipes C. Martius, Nov. Gen. 1: 9. 1823]. N. común: Lirio de Agua.

Plants free-floating, sometimes stranded on mud. Vegetative stem very short, with leaves in a rosette, somewhat ascending to widely spreading, petioles typically short, broadly swollen, almost bulbous, filled with aerenchymatous tissue, or when growing in densely crowded populations, then leaves strongly ascending and petioles more elongate, less swollen. Inflorescence a spike. Flowers showy, blue to light blue, with a yellow spot on upper perianth lobe. Perianth lobes 16-37 mm long. Fruit ca. 1.5 long.

Lagunas, lakes, marshes, canals and ditches. Lowlands throughout Costa Rica [Crow 5952, CR, MO, NHA], Mar.-Nov. S. Mex. to Argentina; introd. in se. U.S.A.

Widely cultivated in water gardens and in artificial pools and fountains.

Eichhornia diversifolia (Vahl) Urban, Symb. Antill. 4: 147. 1903. [Heteranthera diversifolia Vahl, Enum. Pl. 2: 44. 1805].

Plants rooted in mud with elongate stems ascending to water surface. Submerged leaves sessile, linear and ribbon-like, alternate, present especially on younger plants, or absent by deterioration (specimens from upper portion of plant, typically collected without the submersed linear leaves). Petiolate leaves typically with blades floating, cordate at base, 1.3-3.2 cm long. Inflorescence spicate, peduncle glabrous. Flowers blue with yellow spot on upper central lobe. Perianth lobes 4-10 mm long. Fruit 0.6-0.8 cm long.

Lagunas, marshy margins of canals and quiet streams. Llanuras Guatusos, San Carlos, Tortuguero; Valles Tempisque, General [Crow 6246, CR, MO, NHA], April. Nicaragua to northern Brazil; Antilles.

Eichhornia heterosperma Alexander, Lloydia 2: 170. 1939.

Aquatic herbs. Plants rooted in mud, with elongate stems ascending to water surface. Submerged leaves cauline, alternate, sessile, linear and ribbon-like, (specimens typically collected without obtaining submersed leaves). Petiolate leaves with petioles strongly bent, holding blades more or less emergent from floating stems, leaf blades 3-9 cm long, cuneate to truncate at base. Inflorescence glabrous or nearly so. Flowers blue, or white, with a violet spot on upper central perianth lobe. Perianth lobes 8-10 mm long, margins entire. Fruit ca. 1 cm long.

Lagunas and marshy areas along quiet rivers. Llanura Guatusos; Valle Tempisque [Crow 5987, CR, MO, NHA], Sept., Oct. S. Mex. to northern Brazil; Antilles.

Eichhornia paradoxa (C. Martius) Solms-Laub. in A. DC. and C. DC., Monogr. Phan. 4: 531. 1882. [Pontederia paradoxa C. Martius, in Roemer & Schultes, Syst. Veg. 7: 1144. 1830; Eichhornia costaricana L.D. Gómez & Gómez-Laurito, Phytologia 50: 70. 1981].

Plants emergent in shallow water or rooted in mud near water margin. Vegetative stem short. Leaves basal, ascending, petiolate. Inflorescence umbelliform, with 2-5 flowers. Flowers blue. Perianth lobes 12-15 mm. Fruit ca. 1.5 cm long.

Marshy sites. Known in CR only from 1 km N of P. N. Santa Rosa [Gómez & Gómez-L. 7148, CR]. Guatemala, Costa Rica, Venezuela, Brazil.

Horn, C. N. 1985. A systematic revision of the genus Heteranthera sensu lato. Ph.D. Thesis. University of Alabama.

Ca. 9 spp., New York and Massachusetts to Argentina, chiefly tropical and warm temperate America; Africa; naturalized in Europe; 3 spp. reported for CR.

Stems emergent, floating or creeping, rooted in mud. Submersed leaves sessile, linear, ribbon-like, forming a basal rosette, or, in 1 sp., alternate along the submerged portion of stem. Juveniles consisting of a rosette of linear leaves. Mature plants typically with petiolate leaves (ours). Petiolate leaves floating or emergent, blades reniform to cordate to ovate or narrowly to broadly lanceolate to nearly oval. Inflorescence a few-flowered spike or reduced to a solitary flower, subtended by 2 spathes, the lower leaf-like, the upper forming a sheath. Flowers blue to violet or white. Perianth united into a short tube, 6-lobed. Stamens 3, borne on the perianth tube, 1 larger than the lateral 2, filaments bearing glandular hairs. Fruit a capsule, seeds numerous.

1. Flowers very small, 2-6 mm across, 10-30, borne in an elongate spike, stem of emergent inflorescence glandular...H. spicata

1. Flowers larger, (6)8-32 mm across, solitary or 3-8, borne in a short spike; inflorescence stem glabrous.

2. Leaf blades narrowly to sometimes broadly lanceolate, lacking cordate base; flowers solitary, blue to bluish-white, sometimes white, (10)11-32 mm across, perianth tube 15-44 mm long...H. limosa

 

2. Leaf blades cordate to reniform; flowers in a short spike, white, (6)8-10(13) mm across, perianth tube 5-10 mm long...H. reniformis

Heteranthera limosa (Sw.) Willd., Ges. Naturf. Freunde Berlin Neue Schriften 3: 439. 1801. [Pontederia limosa Sw., Nov. Gen. Sp. Prodr. 57. 1788; Heteranthera limosa var. rotundifolia Kunth; H. rotundifolia (Kunth) Griseb.].

Stems rooted in mud, emergent. Leaves typically forming a basal rosette, blades narrowly to broadly lanceolate to nearly oval. Flowers solitary, blue or white. Perianth tube 15-44 mm long, lobes 5.2-16 mm long. Fruit typically 1.2-1.8 cm long.

Shallow water in lagunas, marshy areas along rivers and canals, and ditches. Lowlands; Guanacaste, Puntarenas coastal plain, Llanura San Carlos, probably occurring widely in lowlands [Crow 6062 CR, MO, NHA], Sept., Oct. Great Plains of North America to Mexico, C. Am., and S. Am.

Heteranthera reniformis Ruíz López & Pavón, Fl. Peruv. 1: 43. 1798.

Plants rooted, stems elongate, typically procumbent, or floating in very shallow water. Leaves cordate to reniform, emergent or floating, 1-4 cm long, 1-5 cm wide. Inflorescence spicate, with 2-8 flowers. Fowers white. Perianth tube 5-10 mm long, lobes 3-6.5 mm long. Fruit 0.8-0.9(1) mm long.

Shallow water in lagunas, marshy areas along rivers and canals, and ditches. Lowlands to moderate elevations, widely throughout Costa Rica [Crow 6140, CR, MO, NHA], flowering throughout the year. Eastern U.S.A. s. to n. Argentina.

Heteranthera spicata C. Presl, Symb. Bot. 1: 18. 1830.

Plants rooted, floatiang or emergent. Vegetative stem short, leaves basal. Petiolate leaves with blades cordate, 2-6 cm long, acute to acuminate at apex, floating or emergent. Inflorescence spicate with 10-30 flowers. Flowers pale blue to white. Perianth tube 2-7 mm long, lobes 1-3 mm long, 5 above and 1 below. Fruit 5-6 mm long.

Transitory ponds. Guanacaste lowlands [Bagaces] and Nicoya Peninsula [Estrada 177, CR, INB, MO], Sept. Mex. and C. Am. to nw. Brazil; Antillas.

Lowden, R. M. 1973. A revision of the genus Pontederia (including Reussia). Rhodora 75: 426-487.

7 spp., ne. N.Am. to Argentina and Chile; natz. in Europe and Australia; 2 spp. reported CR.

Perennial or annual. Stems erect, floating, or creeping on mud, stoloniferous or rhizomatous. Juveniles consisting of a rosette of submersed linear leaves. Emergent or floating leaves petiolate, blades linear or, more often, narrowly to broadly lanceolate to ovate to elliptic, most with sagittate or cordate base. Inflorescence a spike, elongate or nearly globose, subtended by 2 spathes, the lower leaf-like, the upper forming a sheath. Flowers blue to purplish or whitish. Perianth tubular, somewhat zygomorphic, 6-lobed, 2-lipped. Stamens 6, borne at 2 levels on perianth tube, filaments bearing glandular hairs. Fruit a utricle (1-seeded nut, surrounded by persistent, hardened perianth, an anthocarp), with ridges smooth, toothed, or spinulose.

1. Inflorescence elongate, typically 7-10 cm; leaves sagittate; stems emersed or erect on wet shores...P. sagittata

1. Inflorescence short, nearly globose, up to 3.5 cm long; leaves reniform to cordate; stems floating, or procumbent on mudflats...P. rotundifolia

Pontederia rotundifolia L.f., Suppl. Pl. 192. 1782. [Reussia rotundifolia (L.f) Castell.].

Plants rooted, stems floating or procumbent on marshy or wet ground. Petiolate leaves floating or emergent, reniform to cordate, 3-15 cm long. Inflorescence spicate, short, nearly globose, up to 3.5 cm long, with 3-25 flowers. Flowers blue or white. Perianth pilose, tube 5-8 mm, lobes 7-12 mm long, upper lobe with 2 yellow spots. Fruit 4-5 mm long.

Floating or amphibious in wet soils at margins of pools and ponds, shores of rivers, edges of canals, and marshy areas. Lowlands. Limon, Tortuguero, llanura Guatusos [Grayum 9819, CR, MO], Sept. S. Mex. to Argentina.

Pontederia sagittata C. Presl, Reliq. Haenk. 1: 116. 1827. [Pontederia cordata var. sagittata (C. Presl) Schery].

Plants rooted, stems emergent or erect on marshy or wet shores. Petiolate leaves broadly sagittate, blade 8-32 cm long. Inflorescence spicate, elongate, typically 7-10 cm long, many-flowered. Flowers blue to lilac, rarely white. Perianth pilose-glandular, tube 6-7 mm long, lobes 6-8 mm long. Fruit 5-6 mm long.

Margins of streams and ditches. Known only from Llanura Guatusos and Osa Peninsula [Herrera 1538, CR, MO], Feb. S. Mex. to Panama.